This disclosure generally relates to a flow control valve and also relates to a fuel processing apparatus incorporating the flow control valve.
U.S. Patent Application Publication No. 2014/0216574A1 (also published as Japanese Laid-Open Patent Publication No. 2014-149035) discloses a flow control valve that may be used for a fuel vapor processing apparatus. The flow control valve is a relief valve including a positive pressure relieve valve and a negative pressure relief valve for maintaining a pressure within a fuel tank at an appropriate level when the fuel tank is closed. In each of the positive and negative pressure relief valves, an annular seal member is disposed between a valve member and a valve seat. The valve member can move to be seated on the valve seat and can move away from the valve seat. The annular seal member may elastically seal between the valve member and the valve seat when the valve member is seated on the valve seat for closing the valve. The seal member includes an annular base portion attached to the valve member. A seal lip protrudes obliquely inwards in the axial direction from the base portion for elastically contacting the valve seat.
To ensure the sealing property of the seal lip of the seal member, it may be necessary for the seal lip to be formed so as to allow easy elastic deformation to some extent. If, however, the seal lip can easily deform, the seal lip may be turned up when the valve member is in a closing position. The seal lip may be turned up due to the fluid pressure acting on the seal lip in the opposite direction, i.e., a direction radially from the outer side to the inner side. If this occurs, the sealing properties or performance of the seal lip may be deteriorated.
In view of the challenges discussed above, there is a need in the art for a technique of inhibiting turning-up of a seal lip of a seal member to make it possible to achieve an improvement in terms of sealing performance.